My '92 300E is using Mobil 1 synthetic ATF in tranny and Amsoil sythetic in the rear diff. No problems so far. Car is nearing 310,000 km (194,000 mi) having owned it for 140,000 km (87,000 mi).

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ARVY

1999 E430
1999 C230 Kompressor
1992 300E (write-off)
1984 190D 2.2 (sold)